> How can you "artificially manipulate" the price of Bitcoin? By buying lots of it then selling? How can that be bad?

You can spread false news that could bump it in either direction. For example a government is planning legislation around bitcoin or (like in this case) a bank is looking closer at money flowing to/from exchanges. These could drive down the price. On the other hand stories about governments embracing it, a company starting to accept it, or more "positive" bitcoin stories could drive up the price.

I think the point of most pump and dump schemes is getting someone else to buy so that you can sell and leave others holding the bag.

Other scams are probably more like MtGox where the coins don't exist or are routinely stolen.

He addresses in his next points, by causing a news event that drives the price against the dollar up or down.